<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>数组去重</title>
</head>

<body>
  <script>
    let arr = [1, 2, 3, 4, 5, 6, 5, 4, 3, 9, 7, 2]
    for (let i = 0; i < arr.length-1; i++) {
      for (let j = i + 1; j < arr.length; j++) {
        if (arr[i] == arr[j]) {
          arr.splice(j, 1)
          j--
        }
      }
    }
    console.log(arr);

  </script>
</body>

</html>